Rapid tests are generally used devices for qualitative purposes. The popularity of the rapid tests is based on the fact that they are easy-to-use, fast and inexpensive. The function of the rapid test is based on principles presented, for example in patent publications WO 92/01226 and U.S. Pat. No. 5,712,170. The device mentioned in these examples is based on membrane material, which contain all the reagents needed for analyzing a test in such a way that the particle reagent needed for the test is placed on the test strip so that the sample placed on the strip moves in the strip system and dissolves the particle reagent by means of liquid flow. After this, the sample and the particle reagent move ahead in the strip system by means of capillary forces. Molecules attached to the membrane structure bind the particle reagent by the sample, thus forming a coloured figure on the membrane. This principle is presented in many publications, which present the particle reagent placed on the test strip, from which it reacts and moves ahead in the membrane-like structure by means of capillary forces.
Placing the particle reagent in the test structure is useful in applications, in which the most basic properties of the rapid test are that it is user-friendly and it can be industrially copied. On the other hand, the particle reagent placed in the test structure causes significant measuring inaccuracy due to the non-simultaneous detachment and dissolution of the particle reagent. This phenomenon is generally seen especially in those rapid tests that use blood or blood derivatives as samples.
In order to make the rapid tests quantitative, optical reading instruments that are able to convert the intensity of the formed line into a numerical value are used. By comparing the intensity of the formed line to the standard value entered in advance to the device, the device can then conclude the quantity of the substance under measurement in the sample. This technique enables in part quantitative measurements with rapid tests, but it cannot take into account the changes in the preparation and making of the tests, which directly cause inaccuracy to the result. The optical readers used at present can be based on CD camera technique, measuring of reflected light or of fluorescence. In present techniques, the reading of the result may be done by forming a ratio by means of the formed test line in the test strip and control line, and by calculating the result by means of a value entered in advance. However, this technique is also incapable of taking into account the variation among sets of tests in which case the result of the analysis can be inaccurate or false.
The patent application US 2003/0148384 presents a method, in which the rapid test device has been improved by adding a particle reagent into a receptacle, from which it dissolves into the sample under analysis, and flows into the test device after the analysed sample. In the present method, the sample under analysis has to be a particle-like in order for the described method to work. By means of the described method, it is possible to reach a higher analytical sensitivity with particle-like analytes. The method in question does not make it possible to measure the molecules for analysis, which are dissolved in liquid, because in the described method, the particle reagent does not flow into the test device simultaneously with the subject under measurement.
The U.S. Pat. No. 6,080,551 describes an application, in which, by means of a test device, observations are made of different GST protein variants by using labelled particle reagent suspension. In the described technique, a particle reagent is in a solution in a receptacle, in which it reacts with the analyte. In the method, the particle reagent is in liquid form, and it is added in the receptacle with the sample when the test device is used. Due to this, the stability of the particle reagent in long-term storage is very limited, and it has to be added separately to the reacting mixture when the test device is used.
The U.S. Pat. No. 5,571,726 describes a method for preparation of a particle reagent by means of glutaraldehyde. The basic reagent in the method is glutaraldehyde, which forms protein binding chemical groups in the particle. However, said glutaraldehyde is not a necessary element when preparing heavy metal particles since the negatively charged surface of the particles binds itself proteins by strong ionic bonds without glutaraldehyde.
The object of the invention is to present a method for preparing a rapid test, which increases the reliability of the results obtained from the rapid tests, and enables more accurate quantitative measurement than before.